Scanner based optical proximity correction system and method of use

ABSTRACT

A modeling technique is provided. The modeling technique includes inputting tool parameters into a model and inputting basic model parameters into the model. The technique further includes generating a simulated, corrected reticle design using the tool parameters and the basic model parameters. An image of test patterns is compared against the simulated, corrected reticle design. A determination is made as to whether δ 1 &lt;ε 1 , wherein δ 1  represents model vs. exposure difference and ε 1  represents predetermined criteria. The technique further includes completing the model when δ 1 &lt;ε 1 .

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Divisional of U.S. application Ser. No.13/721,910, filed Dec. 20, 2012, which is a Divisional of U.S.application Ser. No. 12/521,651, filed Jun. 29, 2009, which is anational stage of PCT/US2008/051146, filed Jan. 16, 2008, which claimspriority under 35 U.S.C. §119 to U.S. Provisional Application No.60/885,547, filed on Jan. 18, 2007, the contents of which are hereinincorporated by reference in their entirety.

FIELD OF THE INVENTION

The invention generally relates to an optical proximity correction (OPC)system and method of use and, more particularly to modeling techniquesused for scanner based reticle designs.

BACKGROUND OF THE INVENTION

Semiconductor manufacturing is limited by the lithography process, whichprints increasingly finer circuit patterns. In turn, the lithographyprocess is driven by two technologies: wafer lithography equipment andcomputational lithography. Historically, wafer lithography andcomputational lithography have been separate and independent processes,each attempting to optimize the lithography process to produce finercircuit patterns.

In the current generation of microelectronics it has become increasinglymore difficult to produce finer circuit patterns. For example, featuresize, line width, and the separation between features and lines arebecoming increasingly smaller and more difficult to produce in newergeneration technologies, e.g., 45 nm technologies. One of thefundamental reasons for these difficulties is that imaging of integratedcircuit (IC) patterns has become prone to optical proximity effects(OPEs) modifying the images in a interdependent manner where any patterninteracts with imaging of its neighbors. To keep up with the need forsuch finer circuit patterns, Optical Proximity Corrections (OPC)processes have been used to improve image fidelity. The goal of the OPCis to correct OPEs, which cause deterioration of image fidelity ofpatterns used in IC manufacture. However, the accuracy of OPC modelshave not kept pace with the requirements for finer circuit patterns,leading to higher manufacturing costs, increased time to market anddecreased quality in manufacturing. Basically, the OPC models used thusfar are incomplete because they do not include all the factors impactingOPEs.

Basically, the OPC process is governed by a set of optical rules, a setof modeling principles or a hybrid combination of rule-based OPC andmodel-based OPC. In general, current OPC techniques involve setting upan OPC software program with accompanying OPC scripts to produce OPCrules for rule-based OPC, or OPC models for model-based OPC. The OPCprogram carries out computer corrections of initial data set withinformation relating to the desired pattern and manipulates the data setto arrive at a corrected data set. This data set is then used to designa reticle used to manufacture the circuit patterns on a wafer.

However, manipulating the data to arrive at a corrected data set is atime consuming process, requiring an iterative process. This iterativeprocess includes constantly modifying the OPC model setup or OPC rulesto arrive at a desirable OPC model. Typically, this is an intensivelymanual process, requiring best guesses and estimations. For example,during OPC model iterations, OPC engineers try to guess how tocompensate for incompleteness of the OPC model. This is time consumingand prone to errors and/or omissions.

Accordingly, there exists a need in the art to overcome the deficienciesand limitations described hereinabove.

SUMMARY OF THE INVENTION

In a first aspect of the invention, a modeling technique is provided.The modeling technique includes inputting tool parameters into a modeland inputting basic model parameters into the model. The techniquefurther includes generating a simulated, corrected reticle design usingthe tool parameters and the basic model parameters. An image of testpatterns is compared against the simulated, corrected reticle design. Adetermination is made as to whether δ₁<ε₁, wherein δ₁ represents modelvs. exposure difference and ε₁ represents predetermined criteria. Thetechnique further includes completing the model when δ₁<ε₁.

In another aspect of the invention, a system is provided for deployingan application for modeling a design layout. The system includes acomputer infrastructure operable to: generate a simulated, correctedreticle design using tool parameters and basic model parameters; comparean image of test patterns against the simulated, corrected reticledesign; compare model vs. exposure difference with predeterminedcriteria; and complete the model when the model vs. exposure differenceis less than the predetermined criteria.

In still a further aspect of the invention, an exposure apparatus isprovided. The exposure apparatus comprises at least one moduleconfigured to: generate a simulated, corrected reticle design using toolparameters and basic model parameters; compare an image of test patternsagainst the simulated, corrected reticle design; compare model vs.exposure difference with predetermined criteria; and complete the modelwhen the model vs. exposure difference is less than the predeterminedcriteria.

In yet another aspect of the invention, a method is provided forproviding a model. The method includes generating a simulated, correctedreticle design using tool parameters and basic model parameters, andcomparing an image of test patterns against the simulated, correctedreticle design. The method further includes iteratively comparing modelvs. exposure difference and predetermined criteria, and changing atleast one of tool parameters and basic model parameters until the modelvs. exposure difference is less than the predetermined criteria in thecomparing.

In still a further aspect of the invention, a computer program productcomprises a computer usable medium having readable program code embodiedin the medium, and the computer program product includes at least onecomponent to: generate a simulated, corrected reticle design using toolparameters and basic model parameters; and iteratively changing at leastone of the tool parameters and basic model parameters and compare modelvs. exposure difference with predetermined criteria until the model vs.exposure difference is less than the predetermined criteria.

In a further aspect of the invention, a method of making a reticle andsemiconductor device comprises: modifying a simulated, corrected reticledesign using basic model parameters and tool parameters of apredetermined projection tool; creating reticle design data whichrepresents a design of layouts to be imaged for the semiconductordevice; and creating a mask set by comparing the simulated, correctedreticle design and the reticle design data.

In still another embodiment, an OPC design process includes providingscanner parameters of a predetermined projection tool to a softwareprovider; importing the scanner parameters into a software product formaking a design of reticles; and providing the software to asemiconductor device maker for use in the design of the reticles.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in the detailed description whichfollows, in reference to the noted plurality of drawings by way ofnon-limiting examples of exemplary embodiments of the present invention.

FIG. 1 shows a graph of k1 trend versus reticle design solutions forfive generations of integrated circuits;

FIG. 2 shows illuminator related parameters which may be used in themodeling technique in accordance with the invention;

FIG. 3 shows projector lens related parameters which may be used in themodeling technique in accordance with the invention;

FIG. 4a shows thermal aberrations of imaging lens which may be takeninto account in the modeling technique in accordance with the invention;

FIG. 4b graphically shows the effect of thermal aberration to OPE usinga 90 nm line;

FIG. 5 shows a graph of tool parameter sensitivity to OPE which may beused in implementing aspects of the invention;

FIG. 6 shows a flow diagram implementing processes in accordance withembodiments of the invention;

FIG. 7 shows a time advantage of using the optical model techniqueimplemented in accordance with the invention for an OPC design of a newscanner;

FIG. 8 shows the time advantage of using the optical model techniqueimplemented in accordance with the invention for an OPC design for a newdevice;

FIG. 9 shows a comparison of impacts of a conventional optical modelversus an optical model implemented in accordance with the invention;

FIG. 10 is a schematic view illustrating a photolithography apparatusaccording to the invention;

FIG. 11 is a flow chart showing semiconductor device fabrication;

FIG. 12 is a flow chart showing wafer processing;

FIG. 13 shows an OPC design process; and

FIG. 14 shows a certification process in accordance with the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The invention generally relates to a scanner based optical proximitycorrection (OPC) system and method of use. In embodiments, the presentinvention utilizes lithography simulation and OPC models to improvecritical dimension (CD) performance of integrated circuits. In preferredembodiments, the OPC models implementing the techniques described hereinwill improve CD performance of integrated circuits for 45 nm CD andbelow. The present invention can be implemented for any tool such as ascanner or a full field stepper.

To achieve nanometer level CD control with fast turnaround time, thesystem and method of the invention uses more than just traditional inputparameters such as lithography dose, defocus, light source type and lensparameters. For example, the simulation and modeling inputs of theinvention include immersion effects, spectral bandwidth and chromaticaberrations, polarization impacts, global and local flare, wavefrontaberrations, scan synchronization effects, and/or other parameters thatmay impact CD performance, as discussed herein. These parameters can bedetermined for each tool generation, or any individual tool, to increaseits overall efficiency in predicting accuracy of features patteredduring integrated circuit manufacture.

By way of comparison, FIG. 1 shows k1 trend versus reticle designsolutions for five generations of CD over a 17 year period. Thesegenerations include a 400 nm CD (1990), 250 nm CD (1995), 130 nm CD(2000), 65 nm CD (2005) and 45 nm CD (2007). As should be understood bythose of skill in the art, k1 represents the coefficient of howdifficult it becomes to image an integrated circuit. As shown in FIG. 1,as the optical image becomes smaller, the more difficult it becomes toimage the smaller features, e.g., lines, spaces, holes, posts and otherfeatures of the integrated circuit layout. This is exemplified by theless pronounced lines, e.g., “fuzzy” or less sharp lines, in eachsuccessive generation.

To compensate for the difficulty in controlling imaging of smallerfeatures, e.g., due to the reduction in the k1 value, methods have beenintroduced which mitigate the problem of the reduction of the k1 value.For example, in the 400 nm CD generation, no specific technique wasrequired to mitigate the problems associated with the reduction in k1.In the 250 nm CD generation, though, a feature biasing was introducedinto the patterning and pattern modeling techniques. Its role was tocorrect for the optical proximity effect resulting in bias betweenisolated and dense features. However, by the 130 nm generation, featuremodeling was not able to adequately compensate for the difficulty inimaging smaller feature sizes. As such, non-printable sub-resolutionassist features, (SRAF) were introduced into the patterning to mitigatethe problems associated with the reduction in k1. Similarly, by the 65nm CD generation, feature modeling and non-printable sub-resolutionassist features, were not able to adequately compensate for thedifficulty in imaging smaller feature sizes. As such, design formanufacturing (DFM) was introduced into the modeling to mitigate theproblems associated with the reduction in k1. DFM is a set of techniquesautomating a wide of range of IC design layout modifications aiming atimproving fidelity of the patterned images. OPC is a key element of DFM.

In the current CD generation equal to 45 nm and less, prior to theintroduction of the current techniques, only data associated withilluminator layout, numerical aperture, feature biasing, andnon-printable sub-resolution assist features, (SRAF) were used in DFM tomitigate the problems in the reduction in k1. However, it has been foundthat such data is not adequate to mitigate the problems in the reductionin k1. As such, the present invention provides a solution by introducingadditional parameters into the OPC modeling techniques, none of whichwere previously considered by those of skill in the art.

More specifically, the present invention increases reticle designrelated yield, decreases design and manufacturing costs, as well as ICtime to market, and provides more accurate and faster OPC design byincorporating scanner design information and actual imaging toolperformance information into the reticle design modeling. The presentinvention is beneficial to any CD generation, with greatestapplicability when the k1 is less than approximately 0.3.

In embodiments, the newly introduced parameters of the modeling providemore robust IC layout designs, where the imaging is more vulnerable tostatistical and deterministic errors, relative to previous generations.These parameters can be introduced for any tool, or tool generation,thereby providing tool-specific or tool type-specific, customized OPCand OPC verification models. The tool may be, for example, scanners orfull field steppers. In embodiments, the system and method of theinvention uses the following preferred parameters in the modeling of thereticle design:

-   -   Illuminator details such as, for example, intensity distribution        and polarization signature across the pupil (polarization        status);    -   Lens signature as defined in terms of Jones Matrix Map or any        other representation of phase, amplitude and polarization        transformations in the lens;    -   Flare data, including global flare and local flare;    -   Longitudinal chromatic aberrations;    -   Illuminator spectrum;    -   Transverse synchronization errors; and    -   Longitudinal synchronization errors.

Illuminator signature contains information about intensity andpolarization content of each location in the illuminator pupil. TheJones Matrix Map contains information about phase, amplitude andpolarization transformations taking place in the lens of the tool. Thesetransformations represent the following:

-   -   Wavefront aberration: Wavefront aberration refers to distortions        of constant phase plane of waves propagating through the        projection lens. It is important to note that conventional        wavefront aberration techniques are indifferent to polarization,        so the polarization properties and transformations of the wave        have been ignored in the past;    -   Apodization: Apodization represents a change the output        intensity profile of an optical system, and is a complicated        function controlled by certain properties of the lens.        Apodization typically refers to a non-uniform transmission        profile that approaches zero at the edges of the lens pupil;    -   Polarization transformations taking place between various        polarization states propagating through the lens.

In embodiments, the Jones Matrix Map will be defined for each lens inthe projection system; although, in alternative embodiments the JonesMatrix Map can be defined for certain relevant lens in the tool.

The flare data, which comprises local flare and global flare, is straylight, which contributes to the deterioration of quality of the image.Flare typically originates in the lens, though other sources can alsocontribute to the flare. Global flare is independent of the imagedimensions while local flare is dependent on the sizes of the images.Those of skill in the art are capable of measuring the flare data, whichcan now be incorporated into the modeling of the present invention.

As to the longitudinal chromatic aberrations, different colors from theilluminator will form images slightly offset from one another. How muchof an offset there is for each of the different colors is characterizedby the longitudinal chromatic aberrations of the lens. Illuminatorspectrum data takes into account all of the colors used in theprojection system including the intensity distribution versuswavelength, not just a simple approach of conventional systems whichassume that the illumination is monochromatic.

In scanners, transverse and longitudinal synchronization errors,characterized by their moving standard deviations (MSDs), account forthe errors in movement between the reticle and wafer during imageformation. For example, as those of skill in the art will appreciate,both the reticle and the wafer are moved during the imaging of anintegrated circuit in order to expose the entire IC pattern image on thewafer. This movement of the reticle and the wafer has to be veryaccurately synchronized. However, the movement of both the reticle andthe wafer can introduce synchronization errors resulting in imagingerrors and, as such, it is important to account for the synchronizationerrors to accurately predict their impact on imaging of the reticle onthe wafer. Thus, in the present invention, the modeling techniques takeinto account the scanner synchronization errors of both the reticle andthe wafer in order to more accurately predict the reticle imaging on thewafer. In general, the use of interferometric techniques can be used tocapture the synchronization errors.

In further embodiments, the system and method of the invention can useother parameters or alternative parameters in the modeling technique ofthe present invention. For example, the present invention alsocontemplates the following parameters:

-   -   Numerical Aperture (NA) error: NA of an optical system is a        dimensionless number that characterizes the range of angles over        which the system can accept or emit light;    -   Sigma error: Sigma error is the illumination set up error;        and/or    -   Thermal Aberration: Thermal Aberration refers to an effect that        causes light from one point of an object, after transmission        through the system to arrive at a point different than predicted        for the light propagating through a lens without thermal        aberrations, based on thermal conditions of the lens as it is        exposed to light. Thermal aberrations are caused by non-uniform        heating of the lens during optical system operation.

It is also contemplated that field-dependent signature can beintroduced, in embodiments.

Thus, by using the above parameters in the modeling technique of thepresent invention, it is now possible to improve accuracy and increasespeed of the modeling process. More specifically, it is advantageouslypossible to:

-   -   Improve the physical model quality in the model setting process;    -   Provide a more accurate, model based OPC;    -   Provide fast conversion of reticle design with OPE (Optical        Proximity Effect) to test exposure;    -   Provide preliminary OPC based on tool design data without OPE        test exposure;        -   and    -   Provide less number of reticle design iteration cycles.

FIG. 2 shows illuminator related parameters which may be used in themodel in accordance with the invention. More specifically, sourceintensity distribution and Stokes parameters distribution, or any otherform of illuminator polarization signature may be used in the modelingtechniques of the present invention. By way of illustration, FIG. 2shows a light source shape for an annular illuminator 200. As seen, theannular illuminator has a source intensity distribution 205 that variesabout the illuminator. The source intensity distribution appears mostintense in the middle of the light source layout with the edges beingless intense. FIG. 2 further shows the Stokes parameters distribution210. Those of skill in the art understand that the Stokes parameters area set of values that describe the polarization state of electromagneticradiation.

FIG. 3 shows projector lens related parameters which may be used in themodel in accordance with the invention. More specifically, FIG. 3 showsscalar, polarization independent aberration and apodization of a lens300, in addition to the lens Jones Matrix Map 305. Again, theseparameters may be used in the modeling technique of the presentinvention.

FIG. 4a shows thermal aberration of a projection lens which may be takeninto account in the model in accordance with the invention. As shown inFIG. 4a , the image field center and filed right show differentnon-uniform distributions of the thermal aberration. For example, thefield center at 30 minutes is 8.8 mλ RMS; whereas, the field right at 30minutes is 6.1 mλ RMS. These variations may be taken into account in themodeling technique of the present invention.

FIG. 4b graphically shows the effect of thermal aberration to OPE, usinga 90 nm line. In the graph of FIG. 4b , the y-axis or ordinate is theimpact of thermal aberration on OPE and the x-axis or abscissa is pitchin nanometers. More specifically, FIG. 4b shows the image size deltadriven by the thermal aberration between zero minutes and 30 minutes fora variety of pitches.

FIG. 5 shows a graph of OPE sensitivity to imaging tool signatures inaccordance with the invention. More specifically, the graph of FIG. 5shows a typical OPE based on an OPE sensitivity analysis. In FIG. 5,sensitivity to OPE was analyzed for the following parameters: NA, Sigma,wavefront aberration, apodization, polarization aberration, thermalaberration, illuminator polarization status and flare. These impactsshow an OPE range of over a 1.8 nm. In the illustrative graph of FIG. 5,the tool (photolithography apparatus) has been found to be mostsensitive to apodization, polarization aberration and flare, each ofwhich may be used as inputs into the modeling technique of the presentinvention. It is noted that for different patterns, the scale of OPEsensitivities to tool parameters might be different.

Those of skill in the art will appreciate that the tool sensitivityanalysis shown by the graph of FIG. 5 can be performed prior toinputting the parameters into the modeling of the present invention. Thetool sensitivity analysis can also be used with any parametersassociated with the lens signature or other tool parameters of any toolor generation of tools (assuming that each tool in the generation willprovide the same or substantially same results). By performing the toolsensitivity analysis prior to inputting the parameters into themodeling, it is possible to determine the impact of the parameters onthe tool. And, by knowing which parameters impact tool performance, itis possible to limit the inputs to the modeling of the present inventionto those parameters.

Exemplary Processes in Accordance with the Invention

FIG. 6 is a flow diagram showing processing steps of embodiments of theinvention. More specifically, FIG. 6 shows imaging model set up andintegrated circuit (IC) design processes, including OPC and OPCverification in accordance with the invention. Even more specifically,steps 600 through 635 show imaging model set up processes in accordancewith the invention; whereas, steps 640 through 670 show IC designincluding OPC and OPC verification in accordance with the invention. TheOPC set up processes and software, and OPC verification can beimplemented in Electronic Design Automation (EDA) tools or electroniccomputer-aided design tools (ECAD) to more accurately model and toverify a reticle design in accordance with the invention, compared toconventional modeling and verification techniques.

FIG. 6 may equally represent a high-level block diagram of components ofthe invention implementing the steps thereof. The steps of FIG. 6 may beimplemented on computer program code in combination with the appropriatehardware. This computer program code may be stored on storage media suchas a diskette, hard disk, CD-ROM, DVD-ROM or tape, as well as a memorystorage device or collection of memory storage devices such as read-onlymemory (ROM) or random access memory (RAM). The invention can take theform of an entirely hardware embodiment or an embodiment containing bothhardware and software elements (any of which is referred generally as“control program”). The hardware and software elements include acomputer infrastructure configured to implement the functionality of thepresent invention. The invention can also take the form of a computerprogram product accessible from a computer-usable or computer-readablemedium providing program code for use by or in connection with acomputer or any instruction execution system.

At step 600, the tool parameters are input into the model. The toolparameters, for example, may be of the illustrative photolithographyapparatus shown in FIG. 10. This will provide a reticle design layoutfor the specific tool disclosed herein, for example. More specifically,the parameters (data) can include: (i) illuminator details; (ii) lenssignature as defined in terms of Jones Matrix Map representing lenssignature; (iii) local and global flare data; (iv) longitudinalchromatic aberrations; (v) Illuminator spectrum; and (iv) transverse andlongitudinal synchronization errors. Of course and as discussed herein,additional or alternative combinations of parameters may be input intothe model. These other parameters include, for example, (i) NA error;(ii) Sigma error; and/or (iii) thermal aberration. Prior to inputtingthe tool parameters, an OPE sensitivity analysis can be conducted inorder to determine which tool parameters should preferably be used inthe model.

At step 605, basic model parameters are input into the model. The basicmodel parameters include reticle solutions such as used in previousgenerations as discussed with reference to FIG. 1, any and all of whichare not exactly predictive of the behavior of the tool. For example, thebasic model parameters include generic test reticle data, illuminatordata, numerical aperture data, feature biasing data and non-printablesub-resolution assist features, (SRAF). Using the parameters of steps600 and 605, a simulated, corrected reticle design is generated, whichis representative of a reticle design used to provide a target layoutfor imaging ground rules of an intended design.

At step 610, a test pattern is made using a generic test reticle data.The test pattern can include any combination of features such as, forexample, parallel lines, perpendicular lines, and lines of differentspacing and/or dimensions. At step 615, the image of the test patternsis compared against the simulated corrected reticle imaging predictionsbased on the OPC model, e.g., expected wafer image as generated by themodel. By way of one illustrative non-limiting example, a 100 nm reticleline using a test reticle is expected to image as an 80 nm line. This 80nm line can be compared against the image expected from the simulatedreticle model.

At step 620, a determination is made as to whether δ₁<ε₁. δ₁ representsthe model vs. exposure difference and ε₁ represents predeterminedcriteria. The predetermined criteria may be, for example, the desiredaccuracy of the model such as the limit of errors a designer would allowfor the model. If δ₁>ε₁, the basic model parameters can be changed atstep 625 and input into the model at step 605. Alternatively oradditionally, the tool parameters can be changed at step 630 and inputinto the model at step 600. The changes to the tool parameters canadvantageously be used to eliminate a number of iterations previouslyrequired in conventional systems. The steps 600, 605, 610, 620, 625 and630 are repeated until δ₁<ε₁.

Once δ₁<ε₁, the model set is completed at step 635. More specifically,as the model set is completed it is now possible to predict ground rulesof the imaging tool and hence more accurately predict how the image willbe formed using the tool. Thus, in this way, as the model set iscomplete, the set up parameters of the model are now known and can beused for the design of the reticle.

At step 640, a reticle design representing intended IC layout isprovided; that is, a pattern on a glass that should present a design isprovided to the tool. More specifically, at step 645, reticle designdata is input into the OPC tool. The reticle design data includes a setof numbers that represents the design of the layouts to be imaged. Theoutput of step 645 is a layout of reticle with OPCs made accordingly tothe model set in step 635. At step 650, a prediction of OPC'ed reticleimaging is made through the model and at step 655 the exposure resultsof the reticle design are provided. The prediction made through themodel and the exposure results are compared at step 660. At step 665, ifδ₂<ε₂, the reticle design is complete. However, if δ₂>δ₂, the processwill return to step 640, where the reticle has to be re-designed and theIC layout patterns have to be corrected. It should be understood thatδ₂<ε₂ can be different from δ₁<ε₁, as the criteria used during model setup (steps 600-635) and design verification (steps 640-670) may bedifferent. However, δ₂<ε₂ and δ₁<ε₁ play a similar role.

Exemplary Implementation Using the Processes in Accordance with theInvention

The present invention may be implemented using Scanner Signature Files(SSF) used for scanner-based optical proximity correction (OPC). Inimplementation, the scanner signature data impacting image OPE will beextracted from the SSF and used in the model of the present invention.These scanner signatures will include a set of parameters and data setsquantifying different scanner characteristics impacting image formationas described in detail herein. In embodiments, there is a single SSF foreach scanner model or scanner type. The information contained in the SSFis typically confidential and is thus provided to the EDA solutionprovider in encrypted form.

As discussed herein, in embodiments, the SSF will include versions basedon design values and versions based on design data and some metrologyresults. The purpose of versions based on design values is to provide aSSF template to guide integration of the scanner signature data with OPCand OPC verification software. The versions based on design data andsome metrology results represent early assessment of scanner impacts tobe integrated with the OPC software. These versions also represent fieldindependent scanner impacts. Therefore, all scanner-driven adjustmentsto the OPC models extracted from these versions should be applieduniformly across the entire image field. A summary of data included inthese file versions is outlined in Table 1, below, and previouslydiscussed herein.

TABLE 1 Subsystem Data Type/OPE Impact Data Illuminator PolarizationPolarization grid map, and width of azimuthal exclusion zone LensVectorial Aberrations Jones matrix grid map Global flare GF Local FlareFlare PSD a and b Longitudinal Chromatic CA_(z) Aberrations LaserIlluminator Spectrum Spectrum γ_(G), γ_(L) Stage TransverseSynchronization MSD-X and MSD-Y Errors Longitudinal MSD-ZSynchronization Errors

Two sets of scanner impacts can be estimated from the data in the SSF:imaging setup-specific (imaging ID-specific) and scanner model- orscanner type-specific. The scanner setup ID is one element indetermining the adjustments to the OPC models. The ID-specific scannerdata is scanner illuminator signature, combining pupil distribution ofilluminator field and illuminator polarization map.

File Header

The SSF file header contains basic, archiving data provided in any knownformat. Under respective labels, the SSF header can contain informationon:

-   -   scanner body type,    -   SSF version,    -   date of SSF release,    -   wavelength (in nm),    -   refractive index of the medium at the image plane,    -   scanner magnification,    -   number of nodes in the grid map data along X and Y coordinates,    -   number of image field points, and    -   image field coordinates at which the data were collected.

Illuminator Data

In illustrative embodiments, the illuminator data includes top-hatintensity distribution. In embodiments, the ID-specific, polarizedilluminator signatures can be created from the illuminator setupspecifications, illuminator polarization grid maps and instructions orformula specifying intensity distributions across illuminator layout.The SSF includes these polarization grid maps necessary to generate theID-specific illuminator signatures.

In the SSF there will be polarized illuminator grid map for azimuthalpolarization and, depending on the scanner body type, polarizedilluminator grid maps for V-polarized and H-polarized illuminators. Inone illustrative example, the azimuthal polarization illuminator gridmap contained in the SSF has the following exemplary format:

[Azimuthally polarized illuminator] −1.000000 −1.000000 0.0000000.000000 0.000000 0.000000 −1.000000 −0.984375 0.000000 0.0000000.000000 0.000000 −1.000000 −0.968750 0.000000 0.000000 0.0000000.000000 .. . 0.906250 −0.140625 0.794697 1.000000 78.746805 93.3337640.906250 −0.125000 0.812689 1.000000 79.190948 93.451483 0.906250−0.109375 0.824535 0.999999 79.592372 92.296603 0.906250 −0.0937500.827760 0.999997 79.842081 93.570158 0.906250 −0.078125 0.8472491.000000 80.091193 93.678275 .. . 1.000000 0.968750 0.000000 0.0000000.000000 0.000000 1.000000 0.984375 0.000000 0.000000 0.000000 0.0000001.000000 1.000000 0.000000 0.000000 0.000000 0.000000 [End azimuthallypolarized illuminator]

The polarization data starts after “[Azimuthally polarized illuminator]”and runs to “[End azimuthally polarized illuminator]” labels (or itsequivalents). Each row of data represents a single point of theilluminator grid map. The numbers in each row specify the location inthe pupil grid in sigma units (S_(x), and S_(y)), followed byilluminator field amplitude, degree of polarization, polarizationorientation and phase shift between X and Y polarization components.

Following the “[End azimuthally polarized illuminator]” label, thefollowing data may be included:

[Azimuthal exclusion width]

ExAzim

[End azimuthal exclusion width]

Here, ExAzim is the width of the diagonal exclusion zone of segmentedannular illuminator given in degrees.

If V- and H-polarized illuminator polarization grid maps are included inthe SSF, their format can be analogous to the azimuthal grid map formatexcept that the labels at the top and the bottom of the data block willbe replaced by [V polarized illuminator] or [H polarized illuminator]and [End V polarized illuminator] or [End H polarized illuminator] (orits equivalents) respectively, for example. If V- and H-polarized dataare not included in the SSF, the respective data segments will have thefollowing exemplary form:

[V polarized illuminator]

[End V polarized illuminator]

and

[H polarized illuminator]

[End H polarized illuminator].

The polarized illuminator data is collected at the numerical aperturespecified in the file header. In the polarized illuminator grid map datasets, the grid point coordinates, the degree of polarization, and theilluminator field amplitude are unitless, while the polarizationorientation angle and the phase shift between X and Y polarizationcomponents are in degrees.

ID-specific illumination data may be generated in the followingexemplary manner.

-   -   (i) Each illuminator pupil grid point is defined by 6 numbers        such as 0.906250-0.140625 0.794697 1.000000 78.746805 93.333764.        Of these, for example, 0.906250-0.140625 are (S_(x), S_(y))        coordinates of the grid map node, 0.794697 is the illuminator        field amplitude E at that node, 1.000000 represents degree of        polarization P, 78.746805 is the polarization vector azimuth α,        □ and 93.333764 is the phase shift Φ between E_(x) and E_(y)        field amplitude components (α and Φ □ are in degrees).    -   (ii) For (S_(x), S_(y)) illuminator grid point, the two E_(x)        and E_(y) polarization components of E can be expressed as:

E _(x)=(E cos α)exp(−i(ωt−kr))  (1)

E _(y)=(E sin α)exp(−i(ωt−kr+π*Φ/180))  (2)

P degree of polarization indicates that at (S_(x), S_(y)) coordinates,in addition to E_(x) and E_(y), there is (1-P) intensity incoherent toE. The (1-P) fraction of incoherent intensity should be treated asunpolarized power present at (S_(x), S_(y)) illuminator coordinates,contributing to image formation.

Illuminator Polarization Options

Each scanner setup ID specifies the exposure conditions, including lensNA, illuminator type and illuminator polarization. Possible illuminatortypes include conventional, small sigma and off-axis illuminators. Amongoff-axis illuminators, the setup IDs specify annular and multi-poledesigns. Table 2 represents polarization options of various illuminatortypes.

TABLE 2 Unpolarized Azimuthal V-Polarized H-Polarized Conventional ✓ ✓ ✓Small-sigma ✓ ✓ ✓ Annular ✓ ✓ Quadrupole ✓ C-Quadrupole ✓ ✓ Dipole-X⁽¹⁾✓ ✓ ✓ Dipole-Y⁽¹⁾ ✓ ✓ ✓ ⁽¹⁾V, H or azimuthal polarization of dipoleilluminators is set up on the scanner based on its actual capabilitiesdetermined by the scanner model and its installed options.

As shown in Table 2, conventional and small-sigma illuminators areeither unpolarized or V- or H-polarized. Off-axis illuminators, annular,C-quadruple and dipole, are either unpolarized or azimuthally polarized.Quadrupole illuminators are unpolarized.

Unpolarized Illuminators

Unpolarized illuminator data should be generated as illuminationdistributions maps specified by the illuminator layouts determined bythe scanner setup ID. In these cases, two orthogonal, incoherentilluminator fields should be generated at each illuminator grid point.

Polarized Illuminator Signatures

When setup ID calls for azimuthal, V- or H-polarized illuminator, theappropriate illuminator polarization grid map data, contained in the SSFshould be used to generate scanner polarization signature. This can beaccomplished by “masking” the appropriate illuminator grid map to thelayout specified by the imaging setup ID. Masking of the illuminatorlayout is akin to imposing a transparent mask of the shape specified bythe scanner setup ID on the appropriate polarization grid map.

Multipole Illuminators

The poles in a multipole illuminators can have different shapes such as,for example, are bun-shaped. These bun-shapes can be represented asfollows:

$\begin{matrix}{{{Parameters}\text{:}}\begin{matrix}{\sigma_{in}\text{:}} & {{The}\mspace{14mu} {Nearest}\mspace{14mu} {{Point}.}} \\{\sigma_{out}\text{:}} & {{The}\mspace{14mu} {Farthest}\mspace{14mu} {{Point}.}} \\{\varphi \text{:}} & {{Open}\mspace{14mu} {Aperture}\mspace{14mu} {{Angle}.}} \\{\theta^{\prime}\text{:}} & {{Rotation}\mspace{14mu} {{Angle}.}} \\{n\text{:}} & {segments}\end{matrix}{{Polar}\mspace{14mu} {Coordinate}\mspace{14mu} {System}\mspace{14mu} \left( {r,\theta} \right)}{{r^{2} + R_{1}^{2} - {2\; r\; R_{1}{\cos \left\lbrack {2\frac{\theta - \theta^{\prime}}{\varphi}{\sin^{- 1}\left( \frac{R_{2}}{R_{1}} \right)}} \right\rbrack}}} \leq R_{2}^{2}}{R_{1} = {{\frac{\sigma_{out} + \sigma_{in}}{2}\mspace{14mu} R_{2}} = \frac{\sigma_{out} - \sigma_{in}}{2}}}} & \left( {2a} \right)\end{matrix}$

A bun-shape multi-pole illuminator cross section is comprised of all thelocations in illuminator pupil with coordinates (r, t) satisfyinginequality (2 a). Here σ_(in) and σ_(out) represent the radia ofilluminator layout inner and outer edges, φ represents the angular widthof the pole, θ′ represents direction along which the poles are aligned,and n represents the number of poles (segments) in the multipole layout.R₁ and R₂ represent the location of the pole's center and the pole'swidth respectively.

Annular Illuminators

Azimuthally polarized annular illuminators typically are comprised offour quadrants separated by exclusion zones, as should be understood bythose of skill in the art. In one example, the exclusion zones are each20 degrees. The ID-specified annular illuminator signatures could beextracted by masking the appropriate illuminator layout from theilluminator polarization grid map contained in the SSF. In one exemplaryembodiment, masking off four exclusion zones is provided along thediagonal directions.

Lens Signature Data

Lens aberration content, including apodization and polarizationtransformations, is represented by pupil grid map of Jones Matrices.This data has the following exemplary format:

[Jones matrix] −1.300000 −1.300000 0.000000 0.000000 0.000000 0.0000000.000000 0.000000 0.000000 0.000000 −1.300000 −1.279688 0.0000000.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 −1.300000−1.259375 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.0000000.000000 −1.300000 −1.239062 0.000000 0.000000 0.000000 0.0000000.000000 0.000000 0.000000 0.000000 . . . 1.300000 1.259375 0.0000000.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 1.3000001.279688 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.0000000.000000 1.300000 1.300000 0.000000 0.000000 0.000000 0.000000 0.0000000.000000 0.000000 0.000000 [End Jones matrix]

In embodiments, the data starts after “[Jones matrix]” and runs to “[EndJones matrix]” labels (or its equivalents). Each row of data representsone grid point of the pupil Jones Matrix Map. The first two numbers ineach row (NA_(x) and NA_(y)) specify the location in the pupil grid inNA units, followed by the real and imaginary parts of Jones Matrixcoefficients Jxx, Jxy, Jyx, and Jyy. Therefore, each line of datacontains the following information: NA_(x), NA_(y) Re(Jxx), Im(Jxx),Re(Jxy), Im(Jxy), Re(Jyx), Im(Jyx), Re(Jyy), and Im(Jyy). The Jonesmatrix coefficients are unitless.

Lens Chromatic Aberration Data

The impact of chromatic aberrations on imaging is driven by the finitespectral bandwidth of the laser irradiating scanner illuminator.Therefore, the SSF data capturing the impact of chromatic aberrations onimaging can comprise three parameters in the following exemplary format:

[Chromatic Aberrations]

CA_(z) γ_(G) γ_(L)

[End Chromatic Aberrations]

Here, CA_(z) represents the longitudinal chromatic aberrationcoefficient and γ_(G) γ_(L) represent the widths of the Gaussian andLorentzian envelopes of the laser spectrum.

Scanner lens chromatic aberration impact is captured by convolution ofthe I_(CA)(z) images with the laser spectra in the following manner:

$\begin{matrix}{\left. {{I_{C\; A}(z)} = {\int{I\left( {z - {C\; A_{z}*\lambda}} \right)}}} \right){p_{C\; A}(\lambda)}{\lambda}} & (3) \\{{p_{C\; A}(\lambda)} = {C_{N}\frac{\exp \left( {- \left( \frac{\lambda}{\gamma_{G}} \right)^{2}} \right)}{\lambda^{2} + \gamma_{L}^{2}}}} & (4) \\{C_{N} = \frac{\gamma_{L}}{\pi*{\exp \left( \frac{\gamma_{L}}{\gamma_{G}} \right)}^{2}*\left\lbrack {1 - {\frac{2}{\sqrt{\pi}}{\int_{0}^{\frac{\gamma_{L}}{\gamma_{G}}}{{\exp \left( {- t^{2}} \right)}\ {t}}}}} \right\rbrack}} & (5)\end{matrix}$

Here I_(CA)(z) and I(z) are the images impacted by chromatic aberrationsand free of the chromatic aberration impact respectively. CA_(z) is thelongitudinal chromatic aberration coefficient. CA_(z) is given in nm/nm(unitless). p_(CA) (λ) is the laser Gaussian-Lorentzian spectrumenvelopes with coefficients in nm, C_(N) is the spectrum normalizationconstant. The indefinite integration in the formula (3), extending fromplus to minus infinity, should be carried out within finite boundarieslarge enough to provide sufficient level of accuracy to formula (3).

Flare Data

The data for flare contains three parameters in the SSF:

[Flare]

a b GF

[End flare].

Scanner local flare impact can be captured in the following manner

$\begin{matrix}{{I_{L\; F}\left( {x,y} \right)} = {{I_{0}\left( {x,y} \right)} + {4\; \pi^{2}*\begin{bmatrix}{{\int{\int{{I_{0}\left( {{x - x_{0}},{y - y_{0}}} \right)}P\; S\; {F\left( {x_{0},y_{0}} \right)}{x_{0}}{y}}}} -} \\{{I_{0}\left( {x,y} \right)}{\int{\int{P\; S\; {F\left( {x_{0},y_{0}} \right)}{x_{0}}{y_{0}}}}}}\end{bmatrix}}}} & (6) \\{{P\; S\; {F\left( {x_{0},y_{0}} \right)}} = {a*\left\lbrack {\left( \frac{2\; N\; A}{\lambda} \right)*\sqrt{x_{o}^{2} + y_{o}^{2}}} \right\rbrack^{b}}} & (7)\end{matrix}$

Here I₀ (x,y)) and I_(LF)(x,y)) are the flare-free images and imagesimpacted by the local flare respectively. PSF (x,y) is flare pointspread function determined by a and b, flare wavefront coefficients. “a”has units of inverse nm² and “b” is unitless. NA and λ□ are the imagingsetup numerical aperture and scanner wavelength respectively.

The integration in formula (6) should be carried out in such a way that√{square root over (x₀ ²+y₀ ²)} changes from zero to infinity, or itsreasonable approximation.

Global flare is represented as a single parameter expressing its valueas percentage of open frame intensity. The global flare impact isrepresented by the following formula:

I _(GF)(x,y)=I(x,y)_(LF)(1−GF/100)+CA*I _(OF) *GF/100  (8)

Here I(r) is the flare-free image, I_(GF)(r) is the image impacted bythe global flare, CA is average reticle clear area, and I_(OF) is openframe intensity. GF, given in percents, is the global flare level. Localand global flare impacts are anisotropic. And, the value of I_(OF)depends on the imaging setup conditions.

Scanner Synchronization Data

The data for synchronization consists of three parameters included inSSF:

[Synchronization]

σ_(x), σ_(y), σ_(z)

[End synchronization].

Here σ_(x), σ_(y) σ_(z) is given in nanometers, represent scansynchronization moving standard deviations, MSD-x, MSD-y and MSD-z, inx, y, and y directions respectively.

Scanner synchronization impact is captured by convolving the images withthe synchronization error probability distributions in the followingmanner

$\begin{matrix}{{I_{synch}(x)} = {\int{{I\left( {x - x_{o}} \right)}{p_{synch}\left( x_{o} \right)}{x_{o}}}}} & (9) \\{{I_{synch}(y)} = {\int{{I\left( {y - y_{o}} \right)}{p_{synch}\left( y_{o} \right)}{y_{o}}}}} & (10) \\{{I_{synch}(z)} = {\int{{I\left( {z - z_{o}} \right)}{p_{synch}\left( z_{o} \right)}{z_{o}}}}} & (11) \\{{p_{synch}(x)} = \frac{\exp \left( {{{- x^{2}}/2}\; \sigma_{x}^{2}} \right)}{\sqrt{2\; \pi \; \sigma_{x}^{2}}}} & (12) \\{{p_{synch}(y)} = \frac{\exp \left( {{{- y^{2}}/2}\; \sigma_{y}^{2}} \right)}{\sqrt{2\; \pi \; \sigma_{y}^{2}}}} & (13) \\{{p_{synch}(z)} = \frac{\exp \left( {{{- z^{2}}/2}\; \sigma_{z}^{2}} \right)}{\sqrt{2\; \pi \; \sigma_{z}^{2}}}} & (14)\end{matrix}$

Here I_(synch) (x,y,z) and I(x,y,z) are the images with and withoutsynchronization errors respectively, p_(synch) (x,y,z) are the Gaussianprobability distributions of the synchronization errors and σ_(x), σ_(y)and σ_(z) are the synchronization moving standard deviations in x, y,and z respectively, all in nm. The indefinite integration in theformulae 9 through 11, extending from plus to minus infinity, should becarried out within finite ranges large enough to provide sufficientlevel of the formulae accuracy.

The Order of Scanner Impacts

During optical proximity correction, the images should be modified bythe scanner impacts in the following order: chromatic aberrations, localflare, global flare, and synchronization.

Exemplary Advantages of Implementing the Processes in Accordance withthe Invention

FIG. 7 shows the time advantage of using the modeling techniqueimplemented in accordance with the invention for an OPC design of a newscanner before it become available for manufacture. In FIG. 7, theparameters considered in the modeling technique of the present inventionincludes the lens and tool parameters 700, in addition to the basicparameters 705. By using the lens and tool parameters 700, only twoiterations are necessary for OPC design completion, compared to three(or more) iterations for a conventional modeling system. This provides atime advantage to the OPC design completion.

FIG. 8 shows the time advantage of using the modeling techniqueimplemented in accordance with the invention for an OPC design of a newdevice to be manufactured on established imaging tools. In FIG. 8, theparameters considered in the modeling of the present invention includethe lens and tool parameters 700, in addition to the optical proximityeffect (OPE) test exposure (basic modeling parameters) 805. As discussedabove, the use of the lens and tool parameters 700 provides a morerobust predictive model, thereby reducing the number of iterationsneeded to design a reticle for a particular image layout. As such, byusing the lens and tool parameters 400, only two iterations arenecessary for OPC design completion, compared to three (or more)iterations for a conventional modeling system.

FIG. 9 shows a comparison of patterns obtained using a reticlemanufactured from the conventional optical model versus an optical modelimplemented in accordance with the invention. More specifically, FIG. 9shows that a reticle manufactured using a conventional optical model,marked by dash line, produces a T-bar pattern with a narrow spacebetween the bars, marked by solid line, caused by an optical proximityeffect (OPE). Such narrow space is driven by T-bar OPE. In this instancethe prediction of OPE is incorrect and it precludes control of theseparation between the two perpendicular bars of the T-bar feature. Incomparison, the scanner parameter embedded optical modeling technique ofthe present invention accurately corrects OPE. The image of correctlyOPC'ed t-bar shows a wide space between perpendicular bars of the T-barpattern. As such, the pattern created using the reticle from theparameter embedded optical model of the present invention is moreaccurate in providing desire image than that produced by theconventional optical model. And, by initially having a more accurateimage, it is possible to reduce the number of iterations needed tomanufacture the reticle used in the imaging process.

The optical proximity effect (OPE) test exposure includes a simulationexposure and an actual exposure. The simulation exposure means that itis implemented just on a computer without an actual exposure by anactual machine.

Exemplary the System Using a Reticle Designed in Accordance with theInvention

FIG. 10 is a schematic view illustrating a photolithography apparatus(exposure apparatus) 40 in accordance with the present invention. Thewafer positioning stage 52 includes a wafer stage 51, a base 1, afollowing stage 3A, a following stage base 3A, and an additionalactuator 6. The wafer stage 51 comprises a wafer chuck 120 that holds awafer 130 and an interferometer mirror IM. The base 1 is supported by aplurality of isolators 54 (or a reaction frame). The isolator 54 mayinclude a gimbal air bearing 105. The following stage base 3A issupported by a wafer stage frame (reaction frame) 66. The additionalactuator 6 is supported on the ground G through a reaction frame 53. Thewafer positioning stage 52 is structured so that it can move the waferstage 51 in multiple (e.g., three to six) degrees of freedom underprecision control by a drive control unit 140 and system controller 30,and position and orient the wafer 130 as desired relative to theprojection optics 46. In this embodiment, the wafer stage 51 has sixdegrees of freedom by utilizing the Z direction forces generated by thex motor and the y motor of the wafer positioning stage 52 to control aleveling of the wafer 130. However, a wafer table having three degreesof freedom (Z, θx, θy) or six degrees of freedom can be attached to thewafer stage 51 to control the leveling of the wafer. The wafer tableincludes the wafer chuck 120, at least three voice coil motors (notshown), and bearing system. The wafer table is levitated in the verticalplane by the voice coil motors and supported on the wafer stage 51 bythe bearing system so that the wafer table can move relative to thewafer stage 51.

The reaction force generated by the wafer stage 51 motion in the Xdirection can be canceled by motion of the base 1 and the additionalactuator 6. Further, the reaction force generated by the wafer stagemotion in the Y direction can be canceled by the motion of the followingstage base 3A.

An illumination system 42 is supported by a frame 72. The illuminationsystem 42 projects radiant energy (e.g., light) through a mask patternon a reticle R that is supported by and scanned using a reticle stageRS. In one embodiment, the reticle is designed using the modelingtechniques of the present invention. The reticle stage RS may have areticle coarse stage for coarse motion and a reticle fine stage for finemotion. In this case, the reticle coarse stage correspond to thetranslation stage table 100, with one degree of freedom. The reactionforce generated by the motion of the reticle stage RS can bemechanically released to the ground through a reticle stage frame 48 andthe isolator 54, in accordance with the structures described in JP Hei8-330224 and U.S. Pat. No. 5,874,820, the entire contents of which areincorporated by reference herein. The light is focused through aprojection optical system (lens assembly) 46 supported on a projectionoptics frame 75 and released to the ground through isolator 54.

An interferometer 56 is supported on the projection optics frame 75 anddetects the position of the wafer stage 51 and outputs the informationof the position of the wafer stage 51 to the system controller 30. Asecond interferometer 58 is supported on the projection optics frame 75and detects the position of the reticle stage RS and outputs theinformation of the position to the system controller 30. The systemcontroller 30 controls a drive control unit 140 to position the reticleR at a desired position and orientation relative to the wafer 130 or theprojection optics 46. By using the system and method of the presentinvention, accuracy of the interferometer is maintained.

There are a number of different types of photolithographic devices whichcan implement the present invention, e.g., j dry and immersionphotolithography tools. For example, apparatus 70 may comprise anexposure apparatus that can be used as a scanning type photolithographysystem, which exposes the pattern from reticle R onto wafer 130 withreticle R and wafer 130 moving synchronously. In a scanning typelithographic device, reticle R is moved perpendicular to an optical axisof projection optics 46 by reticle stage RS and wafer 130 is movedperpendicular to an optical axis of projection optics 46 by waferpositioning stage 52. Scanning of reticle R and wafer 130 occurs whilereticle R and wafer 130 are moving synchronously but in oppositedirections along mutually parallel axes parallel to the x-axis.

Alternatively, exposure apparatus 70 can be a step-and-repeat typephotolithography system that exposes reticle R while reticle R and wafer130 are stationary. In the step and repeat process, wafer 130 is in afixed position relative to reticle R and projection optics 46 during theexposure of an individual field. Subsequently, between consecutiveexposure steps, wafer 130 is consecutively moved by wafer positioningstage 52 perpendicular to the optical axis of projection optics 46 sothat the next field of semiconductor wafer 130 is brought into positionrelative to projection optics 46 and reticle R for exposure. Followingthis process, the images on reticle R are sequentially exposed onto thefields of wafer 130 so that the next field of semiconductor wafer 130 isbrought into position relative to projection optics 46 and reticle R.

However, the use of apparatus 70 provided herein is not limited to aphotolithography system for semiconductor manufacturing. Apparatus 70(e.g., an exposure apparatus), for example can be used as an LCDphotolithography system that exposes a liquid crystal display devicepattern onto a rectangular glass plate or a photolithography system formanufacturing a thin film magnetic head. Further, the present inventioncan also be applied to a proximity photolithography system that exposesa mask pattern by closely locating a mask and a substrate without theuse of a lens assembly. Additionally, the present invention providedherein can be used in other devices, including other semiconductorprocessing equipment, machine tools, metal cutting machines, andinspection machines.

In the illumination system 42, the illumination source can be g-line(436 nm), i-line (365 nm), KrF excimer laser (248 nm), ArF excimer laser(193 nm) or F₂ laser (157 nm). Alternatively, the illumination sourcecan also use charged particle beams such as x-rays and electron beam.For instance, in the case where an electron beam is used, thermionicemission type lanthanum hexaboride (LaB₆) or tantalum (Ta) can be usedas an electron gun. Furthermore, in the case where an electron beam isused, the structure could be such that either a mask is used or apattern can be directly formed on a substrate without the use of a mask.

With respect to projection optics 46, when far ultra-violet rays such asthe excimer laser is used, glass materials such as quartz and fluoritethat transmit far ultra-violet rays are preferably used. When the F₂type laser or x-rays are used, projection optics 46 should preferably beeither catadioptric or refractive (a reticle should also preferably be areflective type), and when an electron beam is used, electron opticsshould preferably comprise electron lenses and deflectors. The opticalpath for the electron beams should be traced in vacuum.

Also, with an exposure device that employs vacuum ultra-violet radiation(VUV) of wavelength 200 nm or shorter, use of the catadioptric typeoptical system can be considered. Examples of the catadioptric type ofoptical system include the disclosure Japan Patent ApplicationDisclosure No. 8-171054 published in the Official Gazette for Laid-OpenPatent Applications and its counterpart U.S. Pat. No. 5,668,672, as wellas Japanese Patent Application Disclosure No. 10-20195 and itscounterpart U.S. Pat. No. 5,835,275. In these cases, the reflectingoptical device can be a catadioptric optical system incorporating a beamsplitter and concave mirror. Japanese Patent Application Disclosure No.8-334695 published in the Official Gazette for Laid-Open PatentApplications and its counterpart U.S. Pat. No. 5,689,377 as well asJapanese Patent Application Disclosure No. 10-3039 and its counterpartU.S. Pat. No. 5,892,117 also use a reflecting-refracting type of opticalsystem incorporating a concave mirror, etc., but without a beamsplitter, and can also be employed with this invention. The disclosuresin the above-mentioned U.S. patents, as well as the Japanese patentapplications published in the Office Gazette for Laid-Open PatentApplications are incorporated herein by reference.

Further, in photolithography systems, when linear motors that differfrom the motors shown in the above embodiments (see U.S. Pat. Nos.5,623,853 or 5,528,118) are used in one of a wafer stage or a reticlestage, the linear motors can be either an air levitation type employingair bearings or a magnetic levitation type using Lorentz force orreactance force. Additionally, the stage could move along a guide, or itcould be a guideless type stage that uses no guide. The disclosures inU.S. Pat. Nos. 5,623,853 and 5,528,118 are incorporated herein byreference.

Alternatively, one of the stages could be driven by a planar motor,which drives the stage by electromagnetic force generated by a magnetunit having two-dimensionally arranged magnets and an armature coil unithaving two-dimensionally arranged coils in facing positions. With thistype of driving system, either one of the magnet unit or the armaturecoil unit is connected to the stage and the other unit is mounted on themoving plane side of the stage.

Movement of the stages as described above generates reaction forces thatcan affect performance of the photolithography system. Reaction forcesgenerated by the wafer (substrate) stage motion can be mechanicallyreleased to the floor (ground) by use of a frame member as described inU.S. Pat. No. 5,528,118 and published Japanese Patent ApplicationDisclosure No. 8-166475. Additionally, reaction forces generated by thereticle (mask) stage motion can be mechanically released to the floor(ground) by use of a frame member as described in U.S. Pat. No.5,874,820 and published Japanese Patent Application Disclosure No.8-330224. The disclosures in U.S. Pat. Nos. 5,528,118 and 5,874,820 andJapanese Patent Application Disclosure No. 8-330224 are incorporatedherein by reference.

As described above, a photolithography system according to the abovedescribed embodiments can be built by assembling various subsystems insuch a manner that prescribed mechanical accuracy, electrical accuracyand optical accuracy are maintained. In order to maintain the variousaccuracies, prior to and following assembly, every optical system isadjusted to achieve its optical accuracy. Similarly, every mechanicalsystem and every electrical system are adjusted to achieve theirrespective mechanical and electrical accuracies. The process ofassembling each subsystem into a photolithography system includesmechanical interfaces, electrical circuit wiring connections and airpressure plumbing connections between each subsystem. Needless to say,there is also a process where each subsystem is assembled prior toassembling a photolithography system from the various subsystems. Once aphotolithography system is assembled using the various subsystems, totaladjustment is performed to make sure that every accuracy is maintainedin the complete photolithography system. Additionally, it is desirableto manufacture an exposure system in a clean room where the temperatureand humidity are controlled.

Further, semiconductor devices can be fabricated using the abovedescribed systems, by the process shown generally in FIG. 11. In step1101 the device's function and performance characteristics are designed.Next, in step 1102, a mask (reticle) having a pattern is designedaccording to the previous designing step, and in a parallel step 1103, awafer is made from a silicon material. The mask pattern designed in step1102 is exposed onto the wafer from step 1103 in step 1104 by aphotolithography system described hereinabove consistent with theprinciples of the present invention. In step 1105 the semiconductordevice is assembled (including the dicing process, bonding process andpackaging process), then finally the device is inspected in step 1106.

FIG. 12 illustrates a detailed flowchart example of the above-mentionedstep 304 in the case of fabricating semiconductor devices. In step 1111(oxidation step), the wafer surface is oxidized. In step 1112 (CVDstep), an insulation film is formed on the wafer surface. In step 1113(electrode formation step), electrodes are formed on the wafer by vapordeposition. In step 1114 (ion implantation step), ions are implanted inthe wafer. The above-mentioned steps 1111-1114 form the preprocessingsteps for wafers during wafer processing, and selection is made at eachstep according to processing requirements.

At each stage of wafer processing, when the above-mentionedpreprocessing steps have been completed, the following post-processingsteps are implemented. During post-processing, initially in step 1115(photoresist formation step), photoresist is applied to a wafer. Next,in step 1116 (exposure step), the above-mentioned exposure apparatus isused to transfer the circuit pattern of a mask (reticle) to a wafer.Then, in step 11317 (developing step), the exposed wafer is developed,and in step 1118 (etching step), parts other than residual photoresist(exposed material surface) are removed by etching. In step 1119(photoresist removal step), unnecessary photoresist remaining afteretching is removed. Multiple circuit patterns are formed by repetitionof these pre-processing and post-processing steps.

Additional Exemplary Methods

As shown in FIG. 13, as a further embodiment, in the OPC design process,the scanner manufacturer provides scanner parameters to a softwareprovider. The software provider, in turn, imports these into thesoftware for making the design of a reticle. The software providerprovides the software to a semiconductor device maker for use in thedesign of reticles. The method can also include the process ofencrypting the data at any of the steps. In further embodiments, thescanner manufacturer provides a scanner parameter software file formatto the software provider, and provides scanner parameters directly tothe semiconductor device maker. The software provider provides thesoftware to the semiconductor device maker. The device maker imports thescanner parameters into the software for use in the design of reticles.Once again, any of the steps can include encryption.

In even further embodiments, as shown in FIG. 14, a method is providedfor verifying compliance with the scanner parameter file format asdescribed above, and would be used to certify a software provider. Forexample, the steps may include, at step 1400, providing a software fileformat to a software provider or user and, at step 1405, providing a setof sample data in the format. At step 1410, a sample reticle pattern isprovided to the semiconductor device maker and, using the sample data, ascanner model is generated at step 1415. At step 1420, a resultingcircuit pattern is simulated using the scanner model and the samplereticle pattern. At step 1425, simulation results are compared to a setof results known to be accurate (either from an accurate simulation, orfrom actual exposure results) and discrepancies are identified. At step1430, a determination is made as to whether the software provideraccurately represented the scanner.

Although the invention has been particularly discussed in aphotolithography system as an exemplary example, the inventive products,methods and systems may be used in other and further contexts, includingany applications where it is desired to design a reticle such asprecision apparatuses (e.g., photography system). Thus, while theinvention has been described in terms of its embodiments, those skilledin the art will recognize that the invention can be practiced withmodifications within the spirit and scope of the appended claims. Thus,it is intended that all matter contained in the foregoing description orshown in the accompanying drawings shall be interpreted as illustrativerather than limiting, and the invention should be defined only inaccordance with the following claims and their equivalents.

What is claimed is:
 1. A method, comprising: modifying a simulatedreticle design using basic model parameters and tool parameters of apredetermined projection tool; creating reticle design data whichrepresents a design of layouts to be imaged for the a semiconductordevice; and creating a mask set by comparing using the simulated reticledesign and the reticle design data.
 2. The method of claim 1, furthercomprising exposing a semiconductor device using the mask set to form animage of a circuit design on the semiconductor device using thepredetermined projection tool.
 3. The method of claim 1, furthercomprising determining the tool parameters by conducting an opticalproximity effect (OPE) sensitivity analysis.
 4. The method of claim 1,wherein the basic model parameters include at least one of: generic testreticle data; illuminator data; numerical aperture data; feature biasingdata; and non-printable sub-resolution assist features (SRAF).
 5. Themethod of claim 1, wherein the predetermined projection tool is ascanner.
 6. The method of claim 1, wherein the predetermined projectiontool is a full field stepper.
 7. The method of claim 1, wherein the toolparameters include one or more of: illuminator details; lens signatureas defined in terms of Jones Matrix Map representing lens signature;local and global flare data; longitudinal chromatic aberrations;Illuminator spectrum; and transverse and longitudinal synchronizationerrors.
 8. An OPC design process, comprising: providing scannerparameters of a predetermined projection tool to a software provider;importing the scanner parameters into a software product for making adesign of reticles; and providing the software to a semiconductor devicemaker for use in the design of the reticles.
 9. The process of claim 8,further comprising providing a scanner parameter software file format tothe software provider, and providing the scanner parameters directly toa semiconductor device maker.
 10. The process of claim 9, furthercomprising verifying compliance with the scanner parameter file formatby generating a scanner model using a set of sample data, simulating acircuit pattern using a scanner model created from the software togenerate sample reticle pattern and comparing a set of results known tobe accurate with the sample reticle pattern.
 11. A computer programproduct comprising a computer usable medium having readable program codeembodied in the medium, the computer program product includes: modifyinga simulated reticle design using basic model parameters and toolparameters of a predetermined projection tool; creating reticle designdata which represents a design of layouts to be imaged for asemiconductor device; and creating a mask set using the simulatedreticle design and the reticle design data.
 12. The computer programproduct of claim 11, wherein the computer usable medium having readableprogram code embodied in the medium is encrypted.
 13. The computerprogram product of claim 11, wherein the tool parameters include one ormore of the following: (i) illuminator details; (ii) lens signature asdefined in terms of Jones Matrix Map representing lens signature; (iii)local and global flare data; (iv) longitudinal chromatic aberrations;(v) Illuminator spectrum; and (vi) transverse and longitudinalsynchronization errors.
 14. The computer program product of claim 13,wherein the tool parameters further include at least one of: (i) NAerror; (ii) Sigma error; and (iii) thermal aberration.
 15. The computerprogram product of claim 11, further comprising conducting an opticalproximity effect (OPE) sensitivity analysis in order to determine whichtool parameters are to be used in the model.
 16. A system for deployingan application for creating a mask set, comprising: a computerinfrastructure operable to: modify a simulated reticle design usingbasic model parameters of a predetermined projection tool; createreticle design data which represents a design of layouts to be imagedfor a semiconductor device; and create a mask set using the simulatedreticle design and the reticle design data.
 17. A method, comprising:modifying a simulated reticle design using basic model parameters andtool parameters of a predetermined projection tool; creating reticledesign data which represents a design of layouts to be imaged for thesemiconductor device; and creating a mask set using the simulatedreticle design and the reticle design data, wherein the tool parameterscomprise at least one of: illuminator details; lens signature as definedin terms of Jones Matrix Map representing lens signature; local andglobal flare data; longitudinal chromatic aberrations; Illuminatorspectrum; and transverse and longitudinal synchronization errors. 18.The method of claim 17, wherein the tool parameters further include atleast one of: NA error; Sigma error; and thermal aberration.
 19. Themethod of claim 17, further comprising exposing the semiconductor deviceusing the mask set to form an image of a circuit design on thesemiconductor device using the predetermined projection tool.
 20. Themethod of claim 17, further comprising determining the tool parametersby conducting an optical proximity effect (OPE) sensitivity analysis.21. The method of claim 17, wherein the basic model parameters includeat least one of: generic teat reticle data; illuminator data; numericalaperture data; feature biasing data; and non-printable sub-resolutionassist features (SRAF).
 22. The method of claim 17, wherein thepredetermined projection tool is a scanner.
 23. The method of claim 17,wherein the predetermined projection tool is a full field stepper. 24.The method of claim 17, further comprising determining the toolparameters.
 25. The method of claim 17, wherein the illuminator detailscomprise information about intensity and polarization content of eachlocation in the illumination pupil.